335 



siphons, the latter are now placed in the genus Hayhurstia, the type of 

 which, H. deformans, sp. n., occurs on Chenopodiuni and Afriplex in 

 Colorado. A key is given to the four genera, Anuraphis, Del Guerc, 

 Aphis, L. (sens, strict.), UrapJiis, Del Guerc, and Hayhurstia, Del 

 Guerc. 



The following species from Eritrea are figured and described : — 

 MacchiatieUa trifolii, s]). n., and Aphis isabeUina, a]), n., on clover; 

 Aphis helianthijS]). n., A. beccarii,sp. n., on Vicia Java; A.andreinii, 

 sp. n., on Coreopsis; A. tavaresi, Del Guerc. ; Vraphis soryki, Theo., 

 on millet ; Macrosiphum sonchi var. flavomaryinata, n. ; Toxoptera 

 aurantii var. limonii, n., on lemon. 



Italian Graminaceae are infested by Sipha spp., MyzocaUis spp.. 

 Aphis avenae, F., ^. maidis, Fitch, A. maidi-radicis, Forb., A. hordei, 

 Del Guerc, A. tmlpiae, Del Guerc, A. rumicis {papaveris, F.) and 

 Anuraphis pnae, sp. n., from the roots of Poa annua. 



The Aphids which have been recorded as infesting citrus plants are 

 Macrosiphum (Siphonophora) cilrifolii, Ashm., Toxoptera aurantii, 

 Koch., Aphis tavaresi, Del Guerc, A. coohii, Essig, AnHraphis erratica, 

 sp. n., Aphis citricola, sp. n., A. rumicis {papaveris, F.), and A. sym- 

 phyti, SchraiLk. 



The concluding section of this paper records preliminary researches 

 on the following root Aphids : — Neorhizobius ulmiphilus, sp. n., on 

 Ulmus americana and U . campestris ; N. stramineus, sp. n., on barley ; 

 Eriosoma {Schizoneura) ulmi, L., on currant and gooseberry ; and the 

 woolly apple aphis [Eriosoma laniyernm]. Among other factors in the 

 spread of the last-named, Miss Patch has recorded the migration of the 

 spring alatae from the elm to the apple. While leaving this matter 

 open, as further experiments are being made, the author states that 

 three years' experiments, conducted with the object of inducing this 

 migration, have given negative results. Of millions of winged sexu- 

 parae migrating from apple trees in the second half of 1915 only a few 

 stopped under the leaves of nearby elms and even these passed on 

 without leaving sexual descendants while in the following spring no 

 trace of galls was noticed on the new leaves. No better success attended 

 an experiment in which sexuparae were enclosed with apple and elm 

 plants. During this experiment, the alatae were seen to remain near the 

 spot where they had developed, but on cutting the branches, where 

 they had been feeding, they departed and not a single sexual individual 

 nor a hibernating egg could be found. In June 1916 attempts were 

 made to infest an apple tree with alatae from elm galls. The alatae 

 issued from the galls and deposited their young on the leaves and 

 branches of the apple, but all these died. The work is being continued 

 in order to ascertain whether the cycle of this Aphid is completed on 

 wild apple and wild pear, as on certain very small apple plants {Pyrus 

 pumila pdradisiam) hibernating forms never recorded before, with the 

 exception of one figured by Baker, were observed. Insecticides con- 

 taining not less than 5 per cent, of tar oil are very efficacious, but for 

 infestations of long standing, substances must be added which produce 

 emanations injurious to the insects over a long period. Solutions 

 containing unrefined commercial creosote are even better than tar oil 

 and it is important that the roots be laid bare and that the excavation 

 be drenched mth the insecticide, which should also be poured on the 

 excavated soil and this quickly replaced. 



